**Core Concept**
The embryonic period is a critical stage in human development, spanning from fertilization to the end of the eighth week of gestation. During this period, the embryo undergoes complex morphological transformations, including gastrulation, organogenesis, and the formation of major body systems.

**Why the Correct Answer is Right**
The embryonic period is characterized by rapid cell division, differentiation, and morphogenesis. The development of the embryoblast, which gives rise to the embryo proper, is a hallmark of this period. The embryonic period is further divided into several stages, including the cleavage stage, blastula stage, and gastrula stage, each with distinct morphological features. The end of the eighth week marks the transition to the fetal period, during which the major body systems continue to mature and differentiate.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the embryonic period does not extend beyond the eighth week of gestation.
**Option B:** This option is incorrect because the fetal period, not the embryonic period, follows the eighth week of gestation.
**Option C:** This option is incorrect because the embryonic period ends before the major body systems have fully developed.

**Clinical Pearl / High-Yield Fact**
The embryonic period is a critical window of susceptibility to teratogenic agents, which can cause congenital anomalies if exposure occurs during this time. Pregnant women are advised to avoid exposure to potential teratogens, such as certain medications, environmental toxins, and infectious agents.

**Correct Answer: C.